WindowView — Science

Perspectives

(092112)

Stasis
— Genome Repair — A Counter Point to Mutation?

Questions:

Evolution implies
gradual changes occur over time, but is there anything to suggest resistance
to change? That is, do biological beings exhibit any traits to suggest there
are mechanisms at work to maintain a species over time?

Do
many, all, or any species once established in time past, as evident in the
fossil record, show a propensity to change from that time forward?

Short Answer:

One of the interesting
points to glean from plants and any animal species that are preserved in the
fossil record, is their maintenance over time. You can go to a botanical garden
today and see a plant called a cycad. You might think of these as something
looking like a dwarf palm trees, but that's a close approximation for a description
of a remarkably old species. Fossils bearing impressions of cycads of long
ago suggest this plant type has changed very little over time. In fact, some
features (for example the numbers of stomata or 'pore structures' in the leaf
surfaces) can be examined in present day and ancient fossil impressions to
reveal something about differences in growing conditions. But over all, the
species has changed very little.

Stasis is defined in terms of "inactivity, equilibrium, standing or stoppage" and in the case of biological life, this means that a form or type (species) exists over time and maintains no apparent change.

Consider This:

LIVING
FOSSILS

Examples of living
fossils include the horseshoe crab and lungfish. Dr. Denton provides an interesting
discussion concerning the lungfish in Chapter 5 of 'Evolution' (ETC).
Here the living form reveals something that the typical (skeletal, bony) fossil
cannot show us. The living fossils' internal organs (which are a full compliment
of otherwise absent features in a typical fossil) can be considered with respect
to the earliest members of the same species. Lungfish and other examples,
as explained by Denton, appear to reveal a combination of traits (mosaics)
that help little to identify these organisms as intermediate forms and that
gaps between groups remain due to the 'living data' that compliments the ancient
fossil finds.

THEY DON"T SHOW
CHANGE

The real question might not be living fossils prove evolution, but
instead reveal evidence for fixity of type ... stasis ... that is, a lack
of change over time. What then of natural selection, mutations, chance, and
random variation for any species that appears now not to have changed or to have changed very little?

A number of deep sea fish species
and many invertebrates, both terrestrial and aquatic, have been discovered
over the past century but all of them have been very closely related
to already known groups, and in the few exceptional cases, when a quite
a new group of organisms has been discovered, it has invariably proved
to be isolated and distinct and in no sense intermediate or ancestral
in the manner required by evolution. Denton
(ETC) Page 159

DNA and ERROR Correction

Take a minute to consider what occurs at the molecular level. If some species show little to no change over time, how do they maintain themselves? We know mutations occur. Sometimes DNA sequences are not 'read' perfectly. If there is error correction taking place, could such an incredible and marvelous cell function be created by the chance mechanisms often attributed to evolution?

Perhaps the best way to appreciate what does occur at the DNA and cell level is to read about how proof reading of DNA actually does occur in cells of living organisms. After that, we can sit back and reflect on the complexity and even wonder how such function could have been created in the first place!

The
3'_5' exonuclease activity plays a critical role in replication: it
allows the enzyme to proofread the new DNA and cut out any mistakes
it has made. Although the polymerase reads the sequence of the old
DNA to produce new DNA, it turns out that simple base paring allows
about one mistake per thousand base pairs copied. Proofreading reduces
errors to about one in a million base pairs. The question for design
theorists is whether proofreading exonuclease had to be present in
the very first cell. That is, could the first cell, with its required
complement of genes coded for by DNA, have successfully reproduced
for a significant number of generations without a proofreading function? Behe (MC) Page
187

When the chromosomes
duplicate they don't do a perfect job of copying the DNA. They make
about one error every 10,000 base pairs they copy [Darnell et al.
1986]. That's the error rate of a typist if he made one error every
five pages. That error rate might be good enough for the office, but
it's not good enough for genetic transcription. The genetic information
has to be copied much more accurately than that to keep the errors
from building up over the generations.

To reduce the errors, the cell
proofreads the DNA and corrects any errors it made in replication.
But a few errors remain even after the proofreading. They are known
as copying errors, or single-nucleotide substitutions.
They are mutations belonging to a class known as point mutations.
They are few enough for the species to tolerate. With the proofreading,
the copying has a very low error rate from one in a billion to one
in a hundred billion. One error per hundred billion would be like
one error in a fifty million pages of typescript. Fifty million pages
are the lifetime output of about a hundred professional typists. And
that's some proofreading! The cell, or organism, can allow this small
error.*

[* Most evolutionists hold that
these errors even play a positive role; they look on these errors
as the source of the variation in neo-Darwinian theory needs. I disagree;
I think these small errors just represent the limit of the accuracy
with which DNA can be copied. Although I concede that they might play
a role in small-scale evolution, I hold that they play no positive
role in large-scale evolution. As we shall see in the following chapters
random variation cannot lead to large-scale evolution.] Spetner (NBC) Page 38

Quotations
from "Mere Creation" (MC) edited
by William A. Dembski are used by permission
of InterVarsity Press, P.O. Box 1400, Downers
Grove, IL 60515. www.ivpress.com All rights
reserved. No portion of this material may be
used without permission from InterVarsity Press.

Quotations
from " Not By Chance " (NBC) written
by L. Spetner, are used by permission
granted by Dr. Lee Spetner.

Writer / Editor: Dr. T. Peterson, Director,
WindowView.org>

(040408)

For a general listing of books, visit the WindowView Book Page for: Science and Scripture .

References of Interest

Step Up To Life

Time spent looking ... through a window on life and choice ... brings the opportunity to see in a new light. The offer for you to Step Up To Life is presented on many of the web pages at WindowView. Without further explanation we offer you the steps here ... knowing that depending on what you have seen or may yet explore in the window ... these steps will be the most important of your life ...